Posted tagged ‘wind direction’

In the prior post I explained why I’m planning for a bomb size of 10 kilotons. Now I’ll look at the risks from the blast and radiation.

While I believe I have a chance of sustaining no injuries or only minor scathing from the affects of the blast, there are many variables to consider and I’ll return to those risks—from shock, heat, fires and flying debris—at a later time. Ultimately, it may be too difficult to determine risk because of unknown variables. For example, will I be standing next to a window that gets blown out or will I be in an interior room? (The U.S. Dept. of Energy website on the Manhattan Project discusses Hiroshima: “…and the blast wave shattered glass in suburbs twelve miles away.”) In any case, I feel blast affects are secondary to radiation risk, where there is a calculable risk of death.

It’s impossible to know the full risk of radiation without knowing wind direction. If I’m upwind of the blast, the best-case scenario, the risk is from immediate radiation or what’s call “ionizing radiation” (the RAND Corporation report cited below calls it “flash radiation”). I’m having difficulty calculating the precise dose of immediate radiation from 10 kilotons at three miles so, for now, I’ll quote a RAND study, which says the zone of 100% mortality is about a radius of three quarters of a mile: “For a 10-kiloton airburst, everyone will be killed by lethal doses of flash radiation to a distance of 0.7 miles.” This is from the RAND Corporation’s Center for Terrorism Risk Management Policy, page four of a report titled, “Considering the Effects of a Catastrophic Terrorist Attack.”
So, beyond three-quarters of a mile, some live and some die. Even if certain death is unlikely from immediate radiation at three miles, there will be some low level of radiation exposure, which could eventually manifest in health problems. But, at the moment, I feel immediate radiation affects are secondary to “residual radiation,” aka, nuclear fallout. On a bad wind day and sans a fallout shelter, I could be fatally zapped.

“Further downwind from the detonation point, a plume of radioactive debris would spread. Its shape and size would depend on wind and rain conditions, but the area over which people who did not shelter themselves or flee within hours would receive lethal radiation doses within a day would range from five to ten square miles: the area of Brooklyn for New York, northwest Washington for Washington, DC, or the upper peninsula for San Francisco – but the direction from ground zero depending on the wind.”

(Note: I thought fallout begins to hit the ground within 15 minutes so I’m confused about the above phrase, “flee within hours.” I’ll return to the topic of evacuating versus sheltering in place with better information on how quickly I need to evacuate.)

While immediate radiation creates a circular pattern of radiation exposure, fallout creates an oval pattern that moves downwind from the blast. The Preventive Defense Project’s “The Day After” report has a map of Washington, D.C., with two overlapping ovals placed on top of the map to show the approximate fallout patterns. The smaller, dark oval is the 50% fatality zone, and the longer, lighter oval is the 10% fatality zone. The visual isn’t that important to see (on page eight if you want to follow the link above to the study) but the caption to the illustration tells me what I need to know:

“Over 50% of the population within the dark red oval (approximately 5 miles long) would incur fatal radiation in the course of the first day if they stayed unsheltered in that area. Absent elaborate shelters people should leave as soon as possible.

“Over 10% of the population in the lighter oval (about 8 miles long) would incur severe radiation injury, sometimes fatal, in the first day if they stayed unsheltered in that area. Light shelters could offer significant protection. There and nearby, sheltering offers the better option.”

The bottom line for me is that there’s a 50% mortality risk in an area five miles downwind of the blast. I’m three miles from my target so, depending upon conditions, my location has a high risk of death and, short of death, a high risk of severe radiation exposure. I don’t have access to an “elaborate shelter” so, if my target is nuked, I’ll need to jump into action.

Fortunately, I’m upwind from my target so, on most days, I’m at low risk. I could dig up historical weather information to better define my risk, and I may do that in the future; but I’m not sure if calculating risk based on the weather, reliably unpredictable, is a good use of my time. Also, I’m not sure if I’ll be able to convincingly monitor wind direction in the immediate hours after a blast.

I’m beginning to wonder, what if I’m over-reacting? What if the probability of a nuke attack is infinitesimally small?

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